Varied Human Influences on Estuaries, San Francisco Bay, California
Hunters Point, a Superfund site in San Francisco Bay, California, that's heavily contaminated with polychlorinated biphenyls (PCBs), was used as a study area to develop tools and methods to assess contaminated sediments
. The standard method to assess an ecological hazard made analyses very difficult and inconclusive. Therefore, the goal of USGS
scientists and their colleagues was to characterize the relationship between bioavailable PCB (controlled in situ by amendments of activated carbon) and the functional ecology of the benthic community.
Phytoplankton populations in estuaries such as San Francisco Bay, California, are influenced by a host of local stresses that mask plankton responses to global climate change
. The above bar graph shows the months that peak chlorophyll concentrations occurred in 116 coastal water bodies in the northern temperate zone. The distribution is surprisingly even from March through September, although, peaks occurred throughout the year. The distribution shows no characteristic single seasonal pattern, a large departure from the regular seasonal pattern of plants on land that is tightly tied to the annual climate cycle (The graph is a modified version of figure 4 from Cloern and Jassby, 2008).
Three scenarios of potential selenium discharges and bioaccumulation that could result from a proposed extension of the San Luis Drain, California. The DYMBAM model
was used as part of a larger model to develop the scenarios of effects in the San Francisco Bay, California (figure taken from USGS Fact Sheet 2004-3091
Sacramento River, California, is the largest tributary in the San Francisco Bay watershed. USGS
scientists have studied the transport of pesticides in the river to gain insight on the fate of pesticides in San Francisco Bay.
scientist retrieving a water-quality sample from a deep-water sampling chamber (Niskin sampler) on board the USGS
Research Vessel Polaris. Discreet samples are collected from different depths at sampling stations throughout the San Francisco Bay, California. USGS
scientists then determinate dissolved oxygen, suspended particulate matter, and chlorophyll concentrations in the water sample.
Zooplankton sampling to measure the biological production of the Sacramento-San Joaquin River Delta's channels. Zooplankton and other phytoplankton are just one part of the Delta's food web, but they play an important role because they are the base of the rest of the food web.
scientists collecting large-volume water samples from the San Joaquin River, California, for analysis of pesticides in suspended sediments. Between 40 and 280 liters of water were collected in stainless steel milk cans, and the water was processed to isolate suspended sediments for analysis.
scientists getting ready to collect water-quality samples in the Sacramento-San Joaquin River Delta, California. Water-quality monitoring is one of the USGS
's contributions to the CALFED Bay-Delta Ecosystem Restoration Program.
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